Cutting fiberglass is not difficult with proper tools and protection. But you don't have to cut anything to remove the benches- a few screws and they're out. They are supported by a narrow fiberglass lip attached to the shell. You could just leave that in place, perhaps trimmed out with flexible U-molding.
- It's my understanding they are structural, adding rigidity to the rear of the shell. You might want to look underneath the rear and see how little frame supports the back of the trailer. You could always call Scamp and ask.
- They house several important components: fresh water tank, power center and converter, wiring for taillights. What will you do about those?
In short, possible, but I recommend you don't.